All of the options you have described will work. But the devil is in the details.
Logic ICs, FPGAs, or Micros can do the conversion from the STEP and DIR signals to run a stepper. You will need some hardware here; the PC will not output signals that go directly to the transistors/motors. The current to drive these things can quickly get rather large. Start with small steppers (I am not sure which kind of printer you got these from, some printers or copiers have quite large motors.)
A site with several proven designs with schematics and layouts is PMinMO. There are several solutions with varying degrees of logic involved, including a PIC.
www.pminmo.com
If you want to go the Microprocessor route, search for Stepper Motor at Microchip. They have several application notes that are a pretty good read.
www.microchip.com
Steve